Apparatus for fabricating wooden frames

ABSTRACT

The apparatus includes a pair of spaced conveyors for conveying upper and lower frame plates through a pair of nailing assemblies. Each nailing assembly includes a nailing gun pivotal between upper and lower positions whereby nails can be driven through the plate and into a stud disposed between the plates at positions spaced along the width of the plate. The conveyor includes a drive unit for advancing the plates through the nailing assemblies discrete distances of 1.5, 16 or 24 inches. One of the conveyors and nailing assemblies is movable laterally relative to the other conveyor and nailing assembly whereby adjustments in width of the frame undergoing fabrication is accomplished. In use, a stud is butted against retractable stops upstanding between the nailing assemblies. Upon command, clamps carried by the nailing assemblies clamp the stud and frame plates one to the other and the nailing gun automatically drives a nail through the plate into the stud. If two nails are required, the gun automatically pivots to an elevated position to drive the next nail. Upon completion of nailing, the conveyor advances upon command a selected discrete distance whereupon an additional stud is located between the plates for nailing.

United States Patent [191 Jureit et al.

[ Nov. 19, 1974 APPARATUS FOR FABRICATING WOODEN FRAMES [76] Inventors:John Calvin Jureit, 8901 Arvida Ln., Coral Gables, Fla. 33156; Howell J.Cotten, Rt. 1, Box 280, Keswick, Va. 22947; Adolfo Castillo, 7761 SW.18th Ter., Miami, Fla. 33155; Roy Leutwyler, 1016 NW. 43rd St., Miami,Fla. 33127 [22] Filed: Feb. 1, 1973 [21] Appl. No.: 328,605

Abernathy 227/152 X Davis 227/100 Primary Examiner-Granville Y. Custer,Jr. Attorney, Agent, or Firm-Le Blanc & Shur 5 7] ABSTRACT The apparatusincludes a pair of spaced conveyors for conveying upper and lower frameplates through a pair of nailing assemblies. Each nailing assemblyincludes a nailing gun pivotal between upper and lower positions wherebynails can be driven through the plate and into a stud disposed betweenthe plates at positions spaced along the width of the plate. Theconveyor includes a drive unit for advancing the plates through thenailing assemblies discrete distances of 1.5, 16 or 24 inches. One ofthe conveyors and nailing assemblies is movable laterally relative tothe other conveyor and nailing assembly whereby adjustments in width ofthe frame undergoing fabrication is accomplished. In use, a stud isbutted against retractable stops upstanding between the nailingassemblies. Upon command, clamps carried by the nailing assemblies clampthe stud and frame plates one to the other and the nailing gunautomatically drives a nail through the plate into the stud. If twonails are required, the gun automatically pivots to an elevated positionto drive the next nail. Upon completion of nailing, the conveyoradvances upon command a selected discrete distance whereupon anadditional stud is located between the plates for nailing.

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W :|4|8 L L4|e 4|9 RACK CLUTCH T T\ F IG. 434 1 PATENTEL HUV 1 91914 ISHEET 09 1 12 791 APPARATUS FOR FABRICATING WOODEN FRAMES The presentinvention relates to apparatus for fabricating wooden frames andparticularly relates to apparatus for nailing studs between the upperand lower plates of a wooden building frame.

There has been a long-felt need for an efficient and effective machinefor fabricating wooden frames, panels and the like and particularly theinterior and exterior wall frames in wooden building construction. Suchframes usually include upper and lower plates with studs connectingbetween such plates and spaced on predetermined centers, usually 16 or24 inch centers. Exterior or load-bearing frames of this type usuallyhave a pair of lapped upper plates. The exterior and interior frames areof conventional height usually about 8 feet with the studs for theexterior frame about 1.5 inches shorter than the studs for the interiorframes to account for the width of the lapped plate.

The present invention provides effective and efficient apparatus forsuccessively nailing studs between upper and lower wooden plates to fonna completed building frame. To accomplish this, the present inventionprovides a pair of conveyors for locating the plates in lateralregistration with nailing assemblies located on opposite sides of theconveyors. A drive unit for the conveyors includes apparatus foradvancing the same selected discrete distances of 1.5, 16 and 24 incheswhereby the partially completed frame is stepped through the nailingassemblies with the studs between the plates being successively alignedwith the nailing guns carried by the nailing assemblies and nailed. Thedrive unit for the conveyor includes a rack and pinion. Dogs areselectively insertable in the path of movement of the rack whereby theconveyor longitudinally displaces the plates and studs of the partiallycompleted frame in successive accurate longitudinal increments. Thestuds are thus nailed on the exact centers desired. The system preventsany inertia from moving the plates and studs beyond the positionsaligned with the nailing guns. One of the conveyors and thecorresponding nailing assembly on a like side of the apparatus aremovable transversely as desired whereby frames of various heights can befabricated. This width adjustment mechanism includes a discrete widthadjusting means for moving the one conveyor and nailing assemblylaterally a distance of 1.5 inches relative to the other conveyor andnailing assembly thereby providing for immediate set-up when switchingfrom the fabrication of interior to exterior wall panels. The apparatusalso includes a plurality of retractable stops located between thenailing assemblies and against which the studs are butted for alignmentwith the nailing guns.

Each nailing gun includes a carriage for pivoting the gun betweenselected elevations whereby either one or two nails can be driventhrough the plate into the stud. That is, frames can be formed utilizing2X2s, 2X3s, 2X4s or 2X6s. The frames formed of 2X4s and 2X6s usuallyrequire two nails at each side of the frame to secure the plates andstuds one to the other rather than the one nail required at each sidewhen frames formed of 2 2s or 2X3s are utilized. Electrical-hydrauliccontrol circuits are utilized for automatically sequencing the gun fordriving one or two nails as selected. Nails for the guns are providedfrom a nail hopper which singulates nails randomly distributed from anail hopper for successive insertion into the bore of the nail gun.

In operation, the plates are located in nailing position by manualoperation of the conveyor. A stud is then butted against the stopsextended between the nailing assemblies whereby the studs are alignedwith the nailing guns with the plates at right angles thereto betweenthe ends of the studs and the nailing guns. Upon command, clamps engagethe stud ends and the respective plates to align the stud and plates ina common horizontal plane. After this clamping action is completed, theguns are automatically extended to butt the respective plates and toclamp them against respective opposite ends of the stud. A nail is thendriven through each plate and into the corresponding end of the stud. Ifonly one nail is required to secure each plate to the stud in aparticular frame, the nailing guns automatically retract. If two nailsare required to secure each plate to the stud, the control circuitcauses each nailing gun to be elevated to drive a second nail throughthe plate into the stud. Upon completion of either the one or two nailnailing cycles, the clamps are automatically released. Also, uponcompletion of nailing, the stud stops are automatically retractedenabling the partially completed frame to be advanced a discreteselected distance by the conveyors to locate the plates in position forinsertion of the next stud on its exact center in line with the nailingguns for the next nailing cycle.

Accordingly, it is a primary object of the present invention to providenovel and improved apparatus for fabricating wooden frames, panels andthe like.

It is another object of the present invention to provide novel andimproved apparatus for fabricating wooden frames, panels and the likeand particularly for nailing the upper and lower plates to studs in abuilding frame.

It is still another object of the present invention to provide novel andimproved apparatus for fabricating wooden frames and the like whereinthe apparatus is readily and easily adapted for the fabrication offrames of different heights and frames utilizing a wide variety ofdifferently sized framing members.

It is a further object of the present invention to provide novel andimproved apparatus for fabricating wooden frames, panels and the likewherein either one or two nails can be selected for securing each plateto the stud and wherein selection of two nails automatically sequencesthe machine for driving the two nails.

It is a still further object of the present invention to provide noveland improved apparatus for fabricating wooden frames, panels and thelike wherein the partially completed frame is advanced through thefabricating machine in selected incremental distances corresponding tothe center to center spacing of the studs in the frame wherby additionalstuds are successively located on center and in nailing position betweenthe plates.

These and further objects and advantages of the present invention willbe more apparent upon reference to the following specification, claims,and appended drawings, wherein:

FIG. 1 is a plan view of a fabricating machine constructed in accordancewith the present invention and with parts broken out for ease ofillustration;

FIG. 2 is a side elevational view thereof;

FIG. 3 is an enlarged fragmentary plan view of the machine of FIG. 1 andillustrating the drive unit for the conveyor thereof;

FIG. 4 is a fragmentary enlarged side elevational view of the drive unitassembly illustrated in FIG. 3;

FIGS. 5, 6 and 7 are fragmentary enlarged crosssectional views thereofgenerally taken about on lines 5-5, 6-6 and 7-7, respectively, in FIG.3;

FIG. 8 is a fragmentary enlarged cross-sectional view of the nail headassembly with parts broken out and in cross section for ease ofillustration;

FIG. 9 is a cross-sectional view thereof taken generally about on line99 in FIG. 8;

FIG. 10 is a view similar to FIG. 8 and illustrating the nail headassembly in an advanced position fully embedding a nail into the frame;

FIG. 1 1 is a fragmentary cross-sectional view thereof;

FIG. 12 is a fragmentary cross-sectional view with parts broken out incross section of a mechanism for adjusting the width of the conveyor anddrive unit assembly;

FIG. 13 is a fragmentary side elevational view of a nail feed assemblyfor the machine hereof;

whereby the attached conveyor rail 24 L is maintained in a fixedposition. Stand 36 includes a base 42 and a pair of upstanding endbrackets 44 which mount a shaft 46 received through the side channelmembers 26 whereby the conveyor rail 24R is slidable along shaft 46 in alateral direction to obtain selected adjusted positions as set forthhereinafter. The drive sprocket 28 at the forward end of conveyor rail24 R is splined to the square shaft 33 whereby the conveyor rail 24R anddrive sprocket carried thereby are free for transverse movement relativeto shaft 33. Treads 30 carry a plurality of longitudinally spaced lumberdrive members 31 which project above the treads for engagement with theends of the plates of the panel undergoing fabrication. The treads 30carry the frame plates through nailing head assemblies 18 whereat thecross members of the frame, i.e., studs, are nailed to the plates.Guides, not shown, are placed along opposite sides of each of theconveyor treads whereby the plates are retained on the conveyor formovement toward the nail head assemblies 18.

The nailing head assemblies 18 are each carried on a machine base 50 towhich is secured, on the side FIG. 14 is an enlarged cross-sectionalview thereof taken about on line 14l4 in FIG. 13;

FIG. 15 is a plan view thereof;

FIG. 16 is a vertical transverse sectional view of the conveyor andnailing assemblies and further illustrating the width adjustmentmechanism;

FIG. 17 is a cross-sectional view thereof taken about on line 1717 inFIG. 16;

FIGS. 18 and 19 are end and side elevational views respectively, of alumber hold-down mechanism;

FIGS. 20A, 20B and 20C are schematic illustrations of various pneumaticcircuits employed with the present invention;

FIG. 21 is a schematic illustration of a hydraulic circuit for use withthe fabricating machine hereof; and

FIGS. 22A, 22B and 22C taken together constitute a schematicillustrationof the electrical circuit for use with the fabricating machine hereof,the FIGS. 22A, 22B and 22C being arranged end to end and from left toright, respectively, to complete the electrical circuit.

Referring now to the drawings, particularly to FIGS. 1 and 2, there isillustrated a panel fabricating machine constructed in accordance withthe present invention and generally indicated 10. Machine 10 generallyincludes a conveyor 12, a drive unit 14 for the conveyor, a downstreamroller conveyor 16, a nail head assembly 18, a nail feed assembly 20 anda width adjustment assembly 22. Conveyor 12 comprises left-andright-hand laterally spaced conveyor rails 24L and 24R each formed oflaterally spaced elongated channels 26 suitably connected one to theother and having an idler sprocket, not shown, at one end and a drivesprocket 28 (FIGS. 3 and 6) at the opposite end. A conveyor chain 29engages about the idler and drive sprockets and carries tread 30 which,on the upper surface of the conveyor rails, rides on a pair of bearingsurfaces, not shown. Drive sprockets 28R and 28L are coupled to shafts32 and 33 respectively, which are driven by the drive unit assembly 14.Portions of the conveyor rails 24L and 24R are supported by conveyorrail floor stands 34 and 36 respectively. Stand 34 includes a base 38and diagonally upstanding support brackets 40 thereof remote from theconveyor 12, a support base 52 for the drive unit 14. Base 52 carries amounting plate 54 carrying an upright 56 to which a hydraulic motor 58is secured. Forwardly of motor 58 there is mounted a shaft 60 carrying asprocket 62. Shaft 60 is mounted at one end in a bearing 64 carried byplate 54 and at its other end by an air clutch 66. Motor 58 is drivinglycoupled to shaft 60 through a sprocket 68 and chain 70, the chain 70passing over idler sprocket 72. Air clutch 66 carries a drive sprocket74 which, via a chain drive including chain 76 and a sprocket 78 carriedby shaft 32, drives shaft 32 in opposite directions depending upon thedirection of rotation of the output shaft of motor 58. A phasingcoupling 80 couples shaft 32 one to the other whereby the rightandleft-hand conveyors 24R and 24L respectively operate in synchronism onewith the other.

Shaft 60 on the drive unit extends through air clutch 66, through apillow block 82, and drives a second air clutch 84. Clutch 84 mounts oneend of an output shaft 86, the other end of which is carried in abearing 88 mounted on plate 54. Shaft 86 also mounts a drive pinion 90which meshes with a rack 92 slidable along a recess 94 defined byupstanding elongated side and end plates 93 and 95 respectively mountedon plate 54. It will thus be appreciated that by actuation of clitch 84,drive pinion 90 rotates in response to rotation of shaft 60 to sliderack 92 along recess 94 in opposite directions depending upon thedirection of rotation of motor 58. The rack 92 is illustrated in FIG. 3in a zero position, that is, its forward end bears against the forwardwall of recess 94. Spaced along the recess and from the opposite end ofrack 92 at increments of 1.5 inches and 16 inches are dogs 96 and 98carried for sliding movement in transversely extending slides 100 and102, respectively. Brackets 101 and 103 project outwardly from a side 93of recess 94 and mount air-actuated cylinders 104 and 106, respectively.The pistons of cylinders 104 and 106 are connected to the respectivedogs 96 and 98. It will be appreciated that actuation of either cylindercauses the corresponding dog to be inserted into the recess 94 and intothe path of movement of rack 92 preventing further movement thereof. Forreasons to be discussed hereinafter, the end of recess 94 carries a stoppad 108 located precisely 24 inches from the near end of rack 92 whenthe rack is located in its zero position. At each of the 1.5, 16 and 24inch positions along the recess 94, there is also mounted micro-switches110, 112, and 114 which are engaged by the near end of rack 92 when itobtains the respective longitudinal positions.

Accordingly, it will be appreciated that by actuation of cylinder 104 orcylinder 106, the rack can be stopped after 1.5 or 16 inches ofmovement, respectively. The rack is, of course, stopped by stop pad 108after 24 inches of movement. As will become clear from the ensuingdescription, the dogs 96 and 98 and stop'pad 108 are utilized because ofthe inertia of the system and effectively stop the conveyorinstantaneously through conveyor clutch 66 when the rack engages thedogs or stop pad, as the case may be. When stopped by the dogs 96 or 98or stop pad 108, the corresponding micro-switch is actuated. When themicroswitch is actuated, clutch 66 is disengaged whereby the couplingbetween the drive motor 58 and the conveyor drive shaft is broken andthe motor 58 reverses. Clutch 84, however, remains engaged and, withmotor 58 reversed, the pinion 90 drives the rack 92 back to its zeroposition into engagement with a micro-switch 116 which serves todisengage clutch 84. By the foregoing arrangement, it will beappreciated that conveyor drive shaft 32 can be selectively rotated toadvance the plates carried on treads discrete distances of 1.5, 16 and24 inches upon command. It will also be appreciated that slides 100 and102 can be located at other selected positions along the recess 94whereby the conveyor can be advanced other selected discrete distances.Also, spacer blocks can be provided at the end of recess 94 to provide afinal discrete movement other than 24 inches. It will also beappreciated that additional slides containing air-actuated cylinders anddogs can be provided, as desired, wherein any desired number of discretemovements can be obtained.

The downstream conveyor 16 comprises a pair of spaced roller conveyors109L and 109R each including spaced side rails 111 and 112 withlongitudinally spaced rollers connected therebetween. Downstream rollerconveyor 109L is fixed on suitable supports, not shown, while rollerconveyor 109R is mounted for movement in a transverse direction relativeto conveyor 109L. Particularly, conveyor 109R is carried bylongitudinally spaced uprights 113, the lower ends of which mountrollers 114 for movement along a transversely extending back or base116. Accordingly, roller conveyor 109R can be selectively transverselyspaced from fixed roller conveyor 109L and in accordance with thespacing of conveyor 24R from fixed conveyor 24L whereby conveyors 24Rand 109R are maintained in longitudinal registry one with the other.

Referring now to FIGS. 4, 8, 10 and 11, the base 50 of the machineincludes a pair of transversely extending channels 130 spaced one fromthe other and carried on suitable supports 132 (FIG. 16). The upper endsof the channels each mount inwardly projecting plates 134. Each of thenail head assemblies 18L and 18R comprises a pair of generallylongitudinally spaced upstanding C-shaped plates 136 between which ismounted a nailing gun generally indicated 137 and ancillary equipmenttherefor. The plates 136 are carried on a lower mounting plate 138. Eachmounting plate 138 extends inwardly toward the opposite nail headassembly to provide support for a housing 142 described hereinafter.Mounting plate 138L is secured to its mounting plates 134, i.e. bywelding or the like. The mounting plate 138R for nail assembly 18Rcarries a gib 140 whereby the nailing head 18R is slidable on mountingplates 134 transversely along base 50.

Each plate 138 also carries a housing 142 for mounting a pair ofretractable fingers or stops 144, the purpose of which is describedhereinafter. Each housing 142 is connected by a bracket 146 to theC-shaped plates 136. Between the housing 142 and nail head assembly 18on the respective opposite sides of the machine and above bracket 146,extends the forward end portion of the drive conveyor. The conveyorchannels 26 are suitably secured to the nail head assemblies 18 andhousings 142. It will be appreciated from the foregoing that theleft-hand nailing assembly 18L, housing 142L, and conveyor 24L arefixedly mounted relative to base 50. However, the nail head assembly18R, housing 142R and the conveyor 24R carried between housing 142R andnail assembly 18R are carried for transverse sliding movement relativeto base 50.

To adjust the position of the nail head assembly 18R, housing 142R andthe conveyor rail 24R relative to the corresponding left-hand partsthereof, there is provided a width adjustment assembly 22 including, asbest illustrated in FIG. 12, an elongated screw 150 threadedly carryinga mounting bracket 152 secured to the underside of gib 140. Mounted atone end of screw 50 through a self-aligning rod and coupler 154 is ahydraulic cylinder 156 for shifting the screw thread 150 axially adiscrete distance equal to 1.5 inches for reasons noted hereinafter.Cylinder 156 is fixed to base 50 between channels 130. The opposite endof screw thread 150 is splined to a drive coupling 158 carried in abearing 160 mounted in a motor housing 162. Housing 162 is secured to anend plate 163 in turn secured to channels 130. A hydraulic motor 164 iscarried on housing 152 and its shaft 166 is splined to drive coupling158. Accordingly, it will be appreciated that actuation of motor 164drives shaft 166 and hence screw thread 150 in rotary directiondependent upon the direction of rotation of motor 164 whereby bracket152 is displaced axially along thread 150. With the foregoingarrangement, the hydraulic cylinder 156 can be actuated to displace thenail head assembly 18R, housing 142R and the right-hand conveyor 24R adistance of 1.5 inches either inwardly or outwardly depending upon itsinitial position whereas the hydraulic motor can displace these elementsrelative to the corresponding elements on the opposite side of themachine selected distances as desired and within a range determined bythe length of thread 150. The discrete width adjustment of 1.5 inchespermits ready adjustment of the machine for handling exterior andinterior wall panels which differ in width one from the other byapproximately 1.5 inches.

A telescoping lumber support assembly, generally indicated 170 in FIG.16, is provided between the leftand right-hand nailing assemblies 18Land 18R, respectively, and specifically between housings 142L and 142R.The support assembly 170 includes a pair of laterally spaced channels172 suitably secured at one end to housing 142R. One end of another pairof channelshaped members 174 are suitably secured to housing 142]... Theopposite ends of channel members 174 are received within the ends ofchannel members 172. Suitable lateral braces 176 are provided betweenthe channel members 172 and 174 at spaced locations therealong. A tray178 is releasably mounted on top of the channel members 172 and 174.Tray 178 includes a flat upper plate 180, elongated bearing surfaces 182which ride on the upper flanges of the channels 172 and 174, and sideretaining flanges 184. It will be appreciated that tray 178 can be movedalong the channel members 172 and 174 and that when the nail assembly18R, conveyor 24R and housing 142R are displaced laterally along thebase of the machine, the channel members 172 and 174 telescope onewithin the other.

Within each housing 142, there is provided a pair of laterally spacedrisers 186 (FIG. 11). Pivotally connected at the lower end of each riseris an upstanding cylinder 188, the piston rod 190 of which is secured toa stud stop or finger 144. The fingers 144 project through an opening inthe upper wall 192 of each housing 142 and are generally square in crosssection. The fingers 144 are transversely aligned one with the otherwhereby they form abutments for the studs S located between the platesP.

Turning now to FIGS. 8 and 10, nail gun 137 includes a carriage 200having a longitudinally extending central aperture 202 and anail-receiving aperture 204 (FIG. 10) for receiving nails from aflexible line 206 from the nail hopper. The carriage 200 is formed ofdiscrete upper and lower parts with such parts held together by a springin housing 208. Carriage 200 is secured to a gib 210 which is slidablymounted along a bar 212, the gib 210 being T-shaped in cross section andbeing received within a slot at the end of bar 212. Gib 210 has a slotalong a lower portion thereof in which is received a pin 214 carried bybar 212. Gib 210 is biased by a compression spring 218 for movement intothe position illustrated in FIG. 10, that is, in a position advanced tobutt the plate P.

To drive the nails into the plate P, a hydraulic cylinder 220 is carriedon bar 212. Cylinder 220 carries a piston 221 which mounts a bracket222. Bracket 222 carries a nail driving rod 224 which is received withinthe central aperture 202 of the nail gun 137. It will be appreciatedthat actuation of cylinder 220 advances nail driving rod 224 such thatthe end of rod 224 engages a nail within aperture 202 and drives thenail through the forward end of the gun into the plate and stud S.Further, it will be appreciated that full extension of piston 221carried by cylinder 220 causes bracket 222 to butt the rear end of guncarriage 200 and advance the latter relative to bar 212 whereby carriage200 bears against the plate P to clamp it to the stud S. Thus the nailis fully seated only when the plate and stud engage one another. Alsocarried on bracket 222 is a plate 226 (FIGS. 8 and 9). Plate 226 has alower aperture 228 which receives a pull rod 230. One end of pull rod230 is secured to carriage 200 while the other end carries an enlargedhead 232. Plate 226 also carries a downwardly projecting tab 234 whichengages a micro-switch 793 in response to full seating of the nail inthe plate and stud and complete advance of the gun carriage 200 towardthe plate and stud. Thus, to drive a nail into the plate and stud, thecylinder 220 is actuated whereby the compression spring 218 advances thecarriage 200 against the plate. Drive rod 224 thereafter advances thenail in aperture 202 into the plate and stud. Full extension of thecylinder 220 butts bracket 222 against the rear end of gun carriage 200to clamp the forward end of carriage 200 against the plate and stud andensure final seating of the nail with the plate and stud in buttingengagement. Upon full seating of the nail and full advancement ofcarriage 200, tab 234 engages the micro-switch 793 which causes, asexplained hereinafter, the cylinder to retract. Upon retraction ofpiston rod 221, the plate 226 engages the head 232 of pull rod 230 priorto full retraction of piston 221. Thus, rod 230 serves to withdraw orpull the gun carriage 200 back from engagement with the plate, i.e.,back to the position illustrated in FIG. 8, in response to fullretraction of piston 221.

In order to drive two or more nails into the plate and stud dependingupon the size of the panel undergoing the fabrication, nail gun 137 ismounted for pivotal movement whereby it can be shifted vertically toalign another nail in the gun carriage with selected positions along thewidth of the wooden plate. To accomplish this, bar 212 which carriescarriage 200 and ancillary equipment including cylinder 220, ispivotally mounted between the C-frame plates 136 at 240. To maintain thegun at a preselected level or elevation and to shift the gun from oneelevation to another, there is provided a hydraulic cylinder 242pivotally mounted at 244 between plates 136 on a bracket 246. The pistonrod 247 of cylinder 242 is pivotally connected to a clevis 248 securedon the underside of bar 212. Also carried by bar 212 is a pair ofupwardly projecting stops 250 which engage a pin 252 located in selectedopenings along fixed brackets 254. That is, cylinder 242 when actuatedraises bar 212 until brackets 250 engage pins 252 limiting upwardmovement of the entire nailing gun assembly. Openings for the pins 252are provided at selected elevations along brackets 254. When thecylinder 242 is fully retracted, the centerline of the nailing gun, thatis, a line drawn through the axis of the aperture 202 through which thenail emerges for embedment into the plate and stud, inclines downwardlyfor inserting a nail into the plate about /8 inch above the lower edgeof the plate. The pins 252 are located in selective openings such thatwhen the gun carriage is elevated and stopped by the pin, the next nailwill be embedded at the appropriate elevation above the first naildepending upon the size of the lumber being used. For example, whennailing 2X2s, only one nail is utilized and this would be driven intothe plate with the gun carriage in its lowermost position with cylinder242 fully retracted. For a 2X4, two nails are used. The first nail isapplied at a location "/8 inch from the lower edge of the plate and thegun carriage is thereafter raised such that the next nail would belocated a distance about 2% inches from the lower edge of the plate. Fora 2X6, the pin would be located such that the gun carriage would beelevated to embed the second nail a distance about 4% inches from thelower edge of the 2X6 plate. It is a feature hereof that the axis of thenail driving cylinder 220 is located about inches above the tread 30whereby each nail driven into the various standard sized plates will bedriven at an angle. This is advantageous in that the resistance towithdrawal of the nail is increased due to its angled insertion. Also,when two nails are driven, they provide a clinching action in securingthe plate and stud one to the other.

Referring now to FIGS. l3, l4 and 15, one of the left and right-handnail feed assemblies 20 is illustrated. Each assembly comprises a hopper260 for receiving randomly distributed nails. Hopper 260 is pivoted atits upper end between a pair of main plates 262 by means of brackets 264and pins 266. Main plates 262 are, of course, secured to the C-frameplates 136 of the nail assembly 18. The hopper has a longitudinallyextending slot 268 in which the randomly distributed nails are receivedwith the shank portions of the nails extending through the slots and thenails being held by the heads engaging along the margins of the slot. Atthe forward end of the hopper 260 there is provided a main gate 270having a notch 271 along its lower edge for permitting the head of eachnail to pass through the notch. Guide tracks 272 are connected to anescapement generally indicated 274. The guide tracks 272 are spaced suchthat the nails received in the guide tracks are singulated one behindthe other with the nails depending from their heads through the slot 276between the guides.

To distribute the nails from hopper 260 into slot 276, the hopper 260 iscontinuously oscillated between the illustrated downwardly inclinedposition and a position wherein the bottom of the hopper formsessentially a continuation of tracks 272. To accomplish thisoscillation, there is provided an eccentric including an arm 278 pivotedat one end to the bottom of hopper 260 and at its other end to a crank280, the crank being rotated by a hydraulic motor not shown in FIG. 13but schematically represented in FIG. 21 by the motors 181L and 181R forthe left and right hand nail hoppers. It will be appreciated thatrotation of crank 280 oscillates hopper 260 between the aforementionedpositions whereby the nails are singulated along the tracks 272. Thenail escapement 274 for each nail feed assembly 20 is per seconventional and forms no part of the present invention. Furtherdescription thereof is therefore believed unnecessary, it beingsufficient to note that nails are dropped one at a time from each of theleft and right-hand escapements 274 through the associated nail feedline 206 by actuation of the corresponding air cylinder 282 which, inturn, respectively operates spring biased nail picks 284. That is, eachtime the pick is displaced by actuation of a cylinder 282 a nail dropsinto the corresponding nail feed line 206.

Mounted on the inside end of the nailing head assemblies are plate andstud clamps generally indicated 300 (FIGS. 8, l and 11). Particularly, abracket 302 connects between the forward ends of C-frame plates 136. Aclamp cylinder bracket 304 is mounted to bracket 302 by bolts 303.Bracket 304 has a pair of vertically elongated slots 305 by which itsposition relative to bracket 302 can be adjusted as desired. Bracket 304carries an outwardly projecting plate 306 mounting a hydraulic cylinder308, the piston of which extends through plate 306 and carries at itslower end a clamp platen 310. Platen 310 carries a guide rod 312 whichextends upwardly through an opening in plate 306 whereby the platen ismaintained in alignment. The platen face carries a clamp 314 having aserrated or otherwise roughened edge for clamping engagement against thestud S. Clamp 314 is carried in a recess formed in the face of platen312. The remaining portion of the lower face of platen 312 which bearsagainst the plate P is smooth. Thus, when the cylinder 308 is actuatedto engage platen 312 against the plate and stud, the stud is held infixed position by clamp 314 while the plate is free to move inwardlyagainst the end of the stud along the lower surface of platen 310. Thatis, the gun carriage 200 can displace the plate P inwardly along thelower face of platen 312 into engagement with the stud end which is heldin place by clamp 314.

Carried by housings 142 and adjacent the left and right hand nailingassemblies is a pair of stud sensor micro-switches 720 and 716respectively, (switch 720 being illustrated in FIG. 10 while bothswitches are illustrated in FIG. 22B). Each switch includes a head 322which projects above the upper surface of housing 142 and which head isengaged by a stud located in butting engagement against the fingers 144.When the stud is so located, head 322 is depressed to actuate switch 720or switch 716 as the case may be.

Referring to FIGS. 18 and 19, frame hold-down mechanisms are provided onopposite sides of the conveyor downstream of the nail head assemblies tomaintain the partially completed frame on the roller conveyor assembly.Each hold-down mechanism includes a roller 330 pivotally carried on ashaft disposed within sleeve 332. Sleeve 332 is coupled to a sleeve 334pivotally mounted between brackets 336 secured the nail head assembliesfor example by welding to one of the plates 136, whereby the roller ispivotal about the axis of sleeve 334. An air-actuated cylinder 338 ispivotally secured at one end to a bracket 340 secured to the lower sideof the nail head assemblies. The piston rod 342 is secured to a leverarm 344 also carried on sleeve 334. Accordingly, retraction of cylinder338 locates the clamping roller 330 on top of the plate and stud as theyemerge from the nailing head assembly.

Referring now to FIGS. 20A, 20B and 20C, there are illustrated variouspneumatic circuits for the machine hereof. As used in the illustrationof the circuits, the small circles indicate a source of air underpressure. Referring first to FIG. 20B, the stop cylinders 188 areconnected in parallel via lines 400 and 402 which communicate with afour-way, two-position, springretumed, valve 404 actuated by fingersolenoid 413. Air pressure communicates from a source with the valve 404via a line 406. The cylinders 188 are connected with lines 400 and 402via lines 408 and 410, respectively. A pressure regulator 412 isdisposed in line 402. Air is supplied under pressure from the sourcethrough valve 404 to maintain the pistons 190 of cylinders 188, i.e.,fingers 144 in an extended position.

Referring now to FIG. 20C, the 1.5 inch rack stop cylinder 104 iscoupled to the air pressure source via lines 412 and 414 and a four-way,two-position, springreturned valve 416 under control of solenoid 418.The 16 inch rack stop cylinder 106 is connected with the air pressuresource via lines 419 and 422 through a fourway, two-position,spring-retumed valve 424 under' control of solenoid 420. It will beappreciated that both the 1.5 inch and 16 inch rack stop cylinders 104and 106, respectively, are normally maintained in a retracted position.Rack clutch 84 lies in communication with the air pressure source via anair line 426 and a four-way, two-position, spring-retumed valve 428actuated by solenoid 430. Conveyor clutch 66' lies in communication withthe air pressure source via an air line 432 and a four-way,two-position, spring-returned valve 434 under control of solenoid 436.

Referring now to FIG. 20A, the left-hand nail drop cylinder 282L lies incommunication with an air pressure source via lines 438 and 440 and afour-way, twoposition, spring-returned valve 442 under control of asolenoid 446, the piston of the cylinder being normally extended. Theright-hand nail drop cylinder 282R likewise lies in communication withan air pressure source via conduits 447 and 448 and a four-way,two-position, spring-returned valve 450 under control of a solenoid 452,the piston being normally extended. The left-hand nail blast lies incommunication with the air pressure source via a line 454 and a two-waynormally closed spring-return valve 456 operated by solenoid 458. Theright-hand nail blast is similarly connected with the air pressuresource via a line 460 and a two-way, twoposition, spring-return valve462 operated by solenoid 464.

Referring now to FIG. 21, there is illustrated a hydraulic circuitschematic including a hydraulic pump 450 driven by electric motor 452for supplying hydraulic fluid from a source 454 via a main fluid line456. A shut-off valve 458 and a pressure gauge 460 are connected to line456 by line 459. Also, a pressure relief valve 462 lies in communicationwith line 456 via line 464. The left-hand nailing cylinder 220L receivesfluid from pump 450 via a line 466, a four-way, two-position,spring-returned valve 468 in communication with line 466 and operated bysolenoid 470, and a pair of fluid lines 472 and 474 in communicationwith valve 468 and with the opposite ends of cylinder 220L. Similarly,the right-hand nail cylinder 220R receives fluid from motor 450 via aline 476 in communication with main line 456, a four-way, two-position,spring-returned valve 478 in communication vn'th line 476, and a pair offluid lines 480 and 482 in communication with valve 478 and oppositeends of cylinder 220R. Valve 478 is operated by solenoid 484. It will beappreciated that the valves 468 and 478 are normally positioned suchthat pump 450 supplies hydraulic fluid to the right and left-hand nailcylinders 220L and 220R respectively and the pistons carried thereby arenormally retracted.

Connected to fluid line 476 by line 485, is a normally closed four-way,three-position, spring-returned valve 488 operable by solenoids 490 and492. A pair of fluid lines 494 and 496 connect valve 488 with the inletand outlet ports respectively of a reversible hydraulic motor 164. Motor164, as will be recalled, provides for adjustment of the width of thedrive conveyors and nailing head assemblies. It will be appreciated thatactuation of solenoid 492 shifts valve 488 to the left as illustratedwhereby fluid is provided motor 164 to rotate screwthread 150 in onedirection to adjust the width of the drive conveyors and nailing headassemblies. Deenergization of valve 492 permits the valve to return toits spring-returned normally closed position. Conversely, energizationof valve 490 shifts valve 488 to the right as illustrated wherebypressure fluid is supplied via lines 486 and 496 to motor 164 whereby itis driven in a reverse direction. This rotates screwthread 150 in thereverse direction. Thus selective energization of solenoids 490 and 492adjusts the width be: tween the conveyors and nailing head assembliesinfinitely over a range permitting fabrication of wall panels of variousheights including most standard heights.

Fluid line 486 connects with main fluid line 456 and serves to supplyfluid to the 1.5 inch width adjustment cylinder 156, the lift cylinders242, the clamp cylinders 308, and the motors 281L and 281R foroscillating the nail hoppers. Particularly, the 1.5 width adjustmentcylinder 156 communicates with line 486 via a line 488 and a four-way,two-position, spring-returned valve 490 and a fluid line 492. Fluid line494 connects between the opposite end of cylinder 156 and valve 490.Valve 490 is exhausted via a line 496 in communication with a mainexhaust line 498. Valve 490 is under the control of a solenoid 500. Itwill be appreciated that fluid thus flows from pump 450 through valve490 via lines 456, 486, and 488 to one side with fluid line 494exhausting the fluid. The lower ends to lift cylinders 242L and 242Rcommunicate with the pressure fluid in line 486 via lines 504, 506, afour-way, two-position, spring-returned valve 508 operated by solenoid510 and fluid line 512. The opposite sides of the lift cylinderscommunicate with valve 508 via fluid lines 514 and 516. A line 518communicates with valve 508 and exhaust line 498. Thus, it will beappreciated that fluid flows via lines 486, 512, through valve 508 andlines 516, 514 into cylinders 242L and 242R whereby the same arenormally retracted. Upon energization of solenoid 510, valve 508 isshifted to supply pressure fluid via lines 486, 512, 506 and 504 tocylinders 242L and 242R to extend the pistons 247 thereof and henceraise the nailing gun carriages as previously described. Deenergizationof solenoid 510 permits valve 508 to return to the illustrated positionwith pressure fluid supplied to cylinders 242L and 242R via lines 512,516 and 514 and exhausted therefrom via lines 504, 506 and 518.

Fluid line 520 communicates with line 486 and a four-way, two-position,spring returned valve 522 operates by solenoid 524. Fluid line 526communicates with valve 522 and a fluid line 528 which communicates withthe upper end of clamp cylinders 308L and 308R. A pressure-actuatedelectrical switch 530 lies in communication with line 526. Fluid line532 communicates with the lower ends of cylinders 308L and 308R and withvalve 522 via line 534. Fluid line 536 communicates between valve 522and exhaust line 498. Thus, upon energization of solenoid 524 valve 522shifts to provide pressure fluid to clamp cylinders 308L and 308R vialines 486, 520, 526 and 528 while exhausting fluid from the lower endsof the cylinders via lines 532, 534, 536 and 498 whereby the clamp heads310 are extended to engage the plates and stud. Upon deenergization ofsolenoid 524, valve 522 is springreturned to the illustrated positionwhereby the clamp heads are returned to their retracted positions. Line542 serially connects the hopper drive motors 281R and 281L. Thus, thesemotors are on when the hydraulic circuits are actuated.

Pressure fluid also communicates between line 456 and rack and conveyormotor 58 via a four-way, three position, spring returned valve 550 andfluid lines 552 and 554. Valve 550 is actuated by energization of eithersolenoid 642 or solenoid 646. Fluid line 556 communicates with line 558at a juncture between a twoposition, one-way, spring-returned valve 560and a flow control valve 562. Valve 560 is under the control of the fastconveyor solenoid 688. A fluid line 564 communicates with line 558beyond valve 562 and via a line 566 to a reservoir. Upon energization ofthe motor forward solenoid 646, valve 550 is shifted to provide pressurefluid from line 456 to motor 58 via line 552 to advance the conveyorwith the fluid exhausting from motor 58 via lines 554, 556 and 558through the flow control valve 562 to the reservoir. When the fastconveyor solenoid 688 is energized, valve 560 shifts to exhaust fluidfrom motor 58 via line 558 whereby motor 58 will speed up. Uponde-energization of solenoids 646 and 688, the valves 550 and 560 returnto their illustrated positions. Upon energization of solenoid 642, valve550 is shifted to provide pressure fluid from line 486 to motor 58 vialine 554 with fluid exhausting through lines 552, 556 and 566. Thisoperates motor 58 in the reverse direction to return the rack 92 to itsinitial position. De-energization of solenoid 642 permits valve 550 toreturn to its spring-retumed position.

ELECTRICAL CONTROL CIRCUIT Referring now to FIGS. 22A, 22B and 22C whichare schematic representations of an electrical control circuit for themachine hereof, the circuit is illustrated in a detached contact modewherein the various relays represented by circles open and closeassociated contacts in a manner to be described, and wherein time delayrelays represented by squares also open and close associated contacts ina manner to be described, normally open and closed contacts beingdenoted by pairs of parallel lines and slashed pairs of parallel lines,respectively. The contacts have numeral suffixes corresponding to thenumeral suffixes of their actuating relay, the second numeral suffixindicating a particular set of the contacts closed and opened by theparticular relay designated by the first numeral suffix. Power isprovided across line 600 and a reference potential by a suitable powersource, not shown. Connected across the power supply in line 602 arenormally closed contacts R9-l and R7-1, a normally open 1.5 inch commandswitch 604, relay R1, normally closed contacts R3-2 and R2-2. Line 606is connected to line 602 between contacts R9-1 and R7-1 and seriallyconnects a 1.5 inch movement complete switch 608, normally open contactsRl-l and relay R4. Line 610 connects with line 602 between relay R1 andswitch 604 and with line 606 between contacts Rl-l and relay R4. Line612 serially connects fuse F1 and a 1.5 inch stop solenoid 418 betweenline 610 and the reference potential. Line 614 connects with line 602between switch 604 and contacts R7-1. A normally open 16 inch commandswitch 616, a relay R2, and normally closed contacts Rl-2 and R3-3 areserially connected in line 618 and between line 614 and the referencepotential. Line 620 serially connects a normally open 24 inch commandswitch 622, relay R3, and normally closed contacts R2-3 and Rl-3 betweenline 614 and the reference potential. Connected to line 606 across thepower supply is line 624 which connects in series a normally closed 16inch movement complete switch 626, nonnally open contacts R2-1 and arelay R5. Line 628 connects with line 618 between relay R2 and switch616 and with line 624 between contacts R2-l and relay R5. Connected inseries between line 628 and the reference potential and in line 630 in afuse F2 and a 16 inch stop solenoid 420. Also connected to line 606across the power supply is a line 632 which serially connects a normallyclosed 24 inch movement complete switch 634, normally open contactsR3-1, and relay R6. Line 636 connects with line 620 between relay R3 andswitch 622 and with line 632 between relay R6 and R3-l. Relay R7 and anormally closed rack zero switch 638 are connected in series in line 639between line 606 and the reference potential. Line 640 connects betweenline 606 and the reference potential and serially connects normally opencontacts R7-l, normally closed contacts TD2-l and TD3-2, nonnally opencontacts TD-4, fuse F3 and a motor reverse solenoid 642. Connectedbetween the reference potential and line 640 between contact TD3-2 andTD-4 is a relay TD4. Normally open contact TD-3, a fuse F4, and a motorforward solenoid 646 are serially connected in line 648 which connectsbetween line 606 and the reference potential. Normally closed contactR11-4 is disposed in line 650 which connects between lines 600 and 652.Connected in parallel between line 652 and line 654 are normally opencontacts R4-2, R5-2, line 654 connecting a relay TDl between suchcontacts and the reference potential. Line 656 connects lines 658 and660 in parallel with line 652.

Line 658 serially connects normally open contacts TD-l, fuse F5 and rackclutch solenoid 430 while line 660 serially connects normally opencontacts TD-2, fuse F6, and conveyor clutch solenoid 436, lines 658 and660 connecting between line 656 and the reference potential. Line 662connects one contact of nonnally open contacts R7-3 with line 650between contacts R1 L4 and the parallel connected contacts R4-2, R5-2and R5-2 and its other contact with line 658 between contacts TD-l andfuse F5. Connected in parallel between line 652 and line 664 arenormally open contacts R4-3, R5-3, R6-3, and R9-2. Line 666 connectsrelay TD2 between line 664 and the reference potential while line 668connects relay J D3 between line 664 and the reference potential. Line670 connects between line 664 and the reference potential and seriallyconnects fuse F7 and the finger solenoid 413. Line 672 connects relay R9and a normally open manual positioning switch 674 in series across line652 and the reference potential. Line 691 connects through line 606 toline 602 between R9-l and R7-1. Disposed serially in line 691 are thenormally closed contacts TDl-2.

Turning back now to FIG. 22A, line 676 serially connects relay R8, anormally closed zero slow switch 680, a normally closed 24 inch slowswitch 682 and a normally closed 16 inch slow switch 684. Line 686connects to line 676 across the power supply and serially connectsnormally open contacts R8-1, fuse F8 and fast conveyor solenoid 688.Line 690 containing normally open contacts R7-4 connects to line 676between switches 682 and 684 and to line 604 between contacts R3-2 andR202. Line 692 containing normally open contacts R3-2 also connects toline 675 between switches 682 and 684 and to line 604 between contactsR3-2 and R2-2.

As will be recalled, the foregoing described circuitry relatesprincipally to the manner of advancing the conveyor either automaticallyin discrete increments of movement or manually. With the circuitenergized as illustrated, assume that it is desired to automaticallyadvance the conveyor 16 inches to locate the partially completed framein position below the nailing heads as more particularly describedhereinafter. The operator presses the 16 inch command switch 616 therebyenergizing relay R2 via lines 600, 602, 614 and 618 and relay R5 vialines 600, 602, 614, 618, 628 and 624. En.- ergization of relay R2 opensnormally closed contacts R2-2 and R2-3 to lock out relays R1 and R1 andenergize the 16 inch stop solenoid 420. This prevents actuation of thecommand circuits through the 1.5 inch and 24 inch command switches 604and 622, respectively. Energization of relay R2 also closes normallyopen contacts R2-l to complete a holding circuit to relay R2 via lines600, 602, 624 and 628 and to relay R5 via lines 600, 602, 606 and 624.Energization of relay R5 closes

1. Apparatus for fabricating a wooden frame, panel or the like having a pair of elongated frame members and a plurality of intermediate members spaced one from the other and extending between the elongated frame members comprising: means for supporting the pair of elongated frame members with an intermediate frame member extending therebetween in a generally common horizontal plane, a pair of nailing assemblies along respective opposite sides of said support means, a nailing gun carried by each of said nailing assemblies, means for actuating each of said nailing guns for driving a nail through the corresponding elongated frame member and into the corresponding end of the intermediate frame member, means mounting said nailing guns for movement between discrete positions for driving nails through each elongated member at different elevations, and means for automatically shifting said nailing guns from one elevation to another elevation in response to completion of nailing at said one elevation in order to drive a nail at said other elevation.
 2. Apparatus according to claim 1 wherein each of said nailing guns is mounted for pivotal movement about an axis spaced from the end thereof through which the nails are driven into the frame members, said shifting means including means for pivoting said guns about said axis whereby the nails at said different elevations are driven in non-parallel directions relative to one another.
 3. Apparatus according to claim 1 including a pair of carriages along respective opposite sides of said support means with each carriage being mounted for linear movement toward and away from the frame members, said nailing guns being carried by said carriage for movement therewith, and means for moving said carriages toward the frame members to engage the ends of said nailing guns against the elongated frame members and clamp the latter against the ends of the intermediate frame member in response to actuation of said nailing machines.
 4. Apparatus according to claim 1 wherein said last mentioned means includes means for shifting the nailing guns from said other elevation back to said one elevation in response to completion of nailing at said other elevation.
 5. Apparatus according to claim 1 wherein said nailing assemblies are fixed to said support means against longitudinal movement, said support means including a conveyor for moving the frame members longitudinally through and relative to said nailing assemblies, means for advancing said conveyor, and means for automatically stopping said conveyor after said conveyor has advanced a predetermined distance equal to the predetermined spacing between the first mentioned and a second intermediate frame member located between the elongated frame members in the completed frame.
 6. Apparatus according to claim 5 including a stop disposed between said nailing assemblies for engagement by an intermediate frame member to transversely align the latter with said nailing guns, and means for moving said stop out of engagement with the intermediate frame member upon completion of nailing thereby enabling the partially completed frame comprised of the elongated frame members and intermediate frame members to be advanced by said conveyor.
 7. Apparatus for fabricating a wooden frame, panel or the like having a pair of elongated frame members and a plurality of intermediate members spaced one from the other and extending between the elongated frame members comprising: means for supporting the pair of elongated frame members with an intermediate frame member extending therebetween in a generally common horizontal plane, a pair of nailing assemblies along respective opposite sides of said support means, a nailing gun carried by each of said nailing assemblies, means for actuating each of said nailinG guns for driving a nail through the corresponding elongated frame member and into the corresponding end of the intermediate frame member, means mounting said nailing guns for movement between discrete positions for driving nails through each elongated member at different elevations, means for automatically shifting said nailing guns from one elevation to another elevation in response to completion of nailing at said one elevation in order to drive a nail at said other elevation, said support means including a conveyor for moving the frame members through said nailing assemblies, means for advancing said conveyor, and means for automatically stopping said conveyor after said conveyor has advanced a predetermined distance equal to the predetermined spacing between the first mentioned and a second intermediate frame member located between the elongated frame members in the completed frame, said stop means including a rack and a pinion for moving the rack along a predetermined path from an initial position, a drive shaft for said conveyor coupled to said pinion and means movable into the path of movement of said rack at selected positions along said path to stop said rack and the conveyor shaft coupled thereto.
 8. Apparatus according to claim 7 including means for returning said rack to its initial position.
 9. Apparatus according to claim 8 wherein said conveyor advance means includes a reversible motor, a first clutch coupling said drive shaft and said reversible motor, a second clutch coupling said drive shaft and said pinion, and means for actuating said clutches to advance said conveyor and said rack when said motor operates in one direction, means for declutching said conveyor drive shaft and said motor when said motor is operated in a reverse direction to return said rack to its initial position.
 10. Apparatus according to claim 5 including means responsive to actuation of said nailing guns for disabling said conveyor advancing means.
 11. Apparatus according to claim 5 including means responsive to actuation of said conveyor advancing means for disabling said nailing gun actuating means and maintaining the same disabled while said conveyor advancing means is actuated to advance the partially completed frame.
 12. Apparatus according to claim 5 including means responsive to actuation of said nailing guns for disabling said conveyor advancing means, means responsive to actuation of said conveyor advancing means for disabling said nailing gun actuating means and maintaining the same disabled while said conveyor advancing means is actuated to advance the partially completed frame.
 13. Apparatus according to claim 1 including means for adjusting the distance between said one elevation and said another elevation for each said nailing gun.
 14. Apparatus according to claim 1 including means carried by each nailing assembly for clamping the corresponding elongated frame member and end of the intermediate frame member to said support means to maintain the frame members in a common horizontal plane.
 15. Apparatus according to claim 14 including a pair of carriages along respective opposite sides of said support means with each carriage being mounted for movement toward and away from the frame members, said nailing guns being carried by said carriage for movement therewith, means for moving said carriage toward the frame members to engage the ends of said nailing guns against the elongated frame members and clamp the latter against the ends of the intermediate frame members, each of said clamping means including a clamping head having a surface for engaging the frame members, the portion of said surface engageable against the corresponding elongated frame member being smooth thereby facilitating clamping of the elongated frame member against the end of the intermediate frame member in response to movement of the corresponding carriage into engagement with the elongated frame member, the portion of said surface engageable against the intermediate frame membEr being roughened to prevent movement of the intermediate frame member when the elongated frame member is clamped thereagainst.
 16. Apparatus according to claim 1 including means for adjustably spacing said nailing assemblies one from the other.
 17. Apparatus according to claim 16 wherein said spacing means comprises means for displacing one nailing assembly relative to the other a discrete predetermined distance.
 18. Apparatus according to claim 17 wherein said spacing means includes a screw carried by said support means and a follower coupled to said screw and said one nailing assembly, said displacing means including a fluid actuated cylinder connected to said screw for axially displacing the latter and said follower a discrete predetermined distance, and means for rotating said screw thereby to displace said follower and the nailing assembly connected thereto over distances other than said discrete distance.
 19. Apparatus for fabricating a wooden frame, panel or the like having a pair of elongated frame members and a plurality of intermediate frame members spaced one from the other and extending between the elongated frame members comprising means for supporting the pair of elongated frame members with an intermediate frame member extending therebetween in a generally common horizontal plane, a pair of nailing assemblies fixed along respective opposite sides of said support means, a nailing gun carried by each nailing assembly, means for actuating each nailing gun for driving a nail through the corresponding elongated frame member and into the corresponding end of the intermediate frame member, a conveyor for moving the frame members relative to and through said nailing assemblies, means for advancing said conveyor and means for automatically stopping said conveyor after said conveyor has advanced a predetermined distance equal to the predetermined spacing between the first mentioned and a second frame member located between the elongated frame members in the completed frame.
 20. Apparatus according to claim 19 including a stop disposed between said nailing assemblies for engagement by an intermediate frame member to transversely align the latter with said nailing guns, and means for moving said stop out of engagement with the intermediate frame member upon completion of nailing thereby enabling the partially completed frame comprised of the elongated frame members and intermediate frame members to be advanced by said conveyor.
 21. Apparatus for fabricating a wooden frame, panel or the like having a pair of elongated frame members and a plurality of intermediate frame members spaced one from the other and extending between the elongated frame members comprising means for supporting the pair of elongated frame members with an intermediate frame member extending therebetween in a generally common horizontal plane, a pair of nailing assemblies along respective opposite sides of said support means, a nailing gun carried by each nailing assembly, means for actuating each nailing gun for driving a nail through the corresponding elongated frame member and into the corresponding end of the intermediate frame member, a conveyor for moving the frame members through said nailing assemblies, means for advancing said conveyor and means for automatically stopping said conveyor after said conveyor has advanced a predetermined distance equal to the predetermined spacing between the first mentioned and a second frame member located between the elongated frame members in the completed frame, said stop means including a rack and a pinion for moving the rack along a predetermined path from an initial position, a drive shaft for said conveyor coupled to said pinion and means movable into the path of movement of said rack at selected positions along said path to stop said rack and the conveyor shaft coupled thereto.
 22. Apparatus accordint to claim 21 including means for returning said rack to its initial position.
 23. Apparatus according to claim 22 wherein said conveyor adVance means includes a reversible motor, a first clutch coupling said drive shaft and said reversible motor, a second clutch coupling said drive shaft and said pinion, and means for actuating said clutches to advance said conveyor and said rack when said motor operates in one direction, means for declutching said conveyor drive shaft and said motor when said motor is operated in a reverse direction to return said rack to its initial position.
 24. Apparatus according to claim 19 including means responsive to actuation of said nailing guns for disabling said conveyor advancing means.
 25. Apparatus according to claim 19 including means responsive to actuation of said conveyor advancing means for disabling said nailing gun actuating means and maintaining the same disabled while said conveyor advancing means is actuated to advance the partially completed frame.
 26. Apparatus according to claim 19 including means responsive to actuation of said nailing guns for disabling said conveyor advancing means, means responsive to actuation of said conveyor advancing means for disabling said nailing gun actuating means and maintaining the same disabled while said conveyor advancing means is actuated to advance the partially completed frame.
 27. Apparatus according to claim 19 including means, carried by each nailing assembly for clamping the corresponding elongated frame member and end of the intermediate frame member to said support means to maintain the frame members in a common horizontal plane.
 28. Apparatus according to claim 27 including a pair of carriages along respective opposite sides of said support means with each carriage being mounted for movement toward and away from the frame members, said nailing guns being carried by said carriage for movement therewith, means for moving said carriages toward the frame members to engage the ends of said nailing guns against the elongated frame members and clamp the latter against the ends of the intermediate frame members, each of said clamping means including a clamping head having a surface for engaging the frame members, the portion of said surface engageable against the corresponding elongated frame member being smooth thereby facilitating clamping of the elongated frame member against the end of the intermediate frame member in response to movement of the corresponding carriage into engagement with the elongated frame member, the portion of said surface engageable against the intermediate frame member being roughened to prevent movement of the intermediate frame member when the elongated frame member is clamped thereagainst.
 29. Apparatus according to claim 19 including means for adjustably spacing said nailing assemblies one from the other.
 30. Apparatus according to claim 29 wherein said spacing means comprises means for displacing one nailing assembly relative to the other a discrete predetermined distance.
 31. Apparatus for fabricating a wooden frame, panel or the like having a pair of elongated frame members and a plurality of intermediate frame members spaced one from the other and extending between the elongated frame members comprising means for supporting the pair of elongated frame members with an intermediate frame member extending therebetween in a generally common horizontal plane, a pair of nailing assemblies along respective opposite sides of said support means, a nailing gun carried by each nailing assembly, means for actuating each nailing gun for driving a nail through the corresponding elongated frame member and into the corresponding end of the intermediate frame member, a conveyor for moving the frame members through said nailing assemblies, means for advancing said conveyor and means for automatically stopping said conveyor after said conveyor has advanced a predetermined distance equal to the predetermined spacing between the first mentioned and a second frame member located between the elongated frame members in the completed frame, means for adjustably spacing said nailing assemblies one from The other, said spacing means comprising means for displacing one nailing assembly relative to the other a discrete predetermined distance, said spacing means including a screw carried by said support means and a follower coupled to said screw and said one nailing assembly, said displacing means including a fluid actuated cylinder connected to said screw for axially displacing the latter and said follower a discrete predetermined distance, and means for rotating said screw thereby to displace said follower and the nailing assembly connected thereto over distances other than said discrete distance.
 32. Apparatus according to claim 5 wherein said conveyor advancing means includes means for advancing the conveyor a plurality of discrete distances, means for stopping said conveyor after advancement thereof a distance equal to each of said discrete distances, and means for selectively actuating said stopping means to advance said conveyor one of said plurality of discrete distances. 